Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria

Dada Abiodun; Okareh Oladapo; Opawade Dolapo; Awopetu Niyi

doi:doi:10.11648/j.ajbio.20261402.13

Research Article |

| Peer-Reviewed

Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria

Dada Abiodun^*

, Okareh Oladapo

, Opawade Dolapo, Awopetu Niyi

Published in American Journal of BioScience (Volume 14, Issue 2)

Received: 16 October 2025 Accepted: 25 March 2026 Published: 15 April 2026

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Abstract

Introduction: Leafy vegetables are a vital part of a balanced diet due to their high nutritional content, including fibre, vitamins, and minerals. However, there are concerns about the safety of the vegetables due to contamination from poor hygienic handling and pesticide residues. Major health problems associated with vegetables that contains pesticides residues are immunological suppression, hormonal changes and occurrence of different cancers. There are limited studies on the safety practices of vegetable handlers and isolated pesticides of raw and cooked vegetables. Hence, this study investigates the hygienic practices among vegetable handlers and levels of pesticide residues in a commonly consumed leafy vegetable. Methods: A descriptive cross-sectional study design and laboratory analysis was used. Through random sampling, 80 vegetable handlers in Bodija market were selected. Data on hygiene knowledge, attitudes and practices were obtained using structured questionnaires. Pesticide residues in Corchorus olitorius vegetable was analyzed using QuEChErs and Gas chromatography-Mass Spectrometry (GC-MS). The data was presented in mean, standard deviation, simple percentage and charts. The result was compared to the Maximum Residue Limits (MRLs) set by Codex Alimentarius Commission. Results: The study shows that 86.3% of respondents were female, and 13.8% were male. Majority of the respondents (82.5%) recognized dirty water used for washing the vegetables as a major source of contamination while 45.0% acknowledged handling with unclean hands as a risk factor, and 30.0% identified pesticides as potential contaminants. Only 65.0% noted poor hygiene could affects quality of vegetable. However, 50.0% practiced hand washing, and 83.8% saw no need to cover their vegetables. The laboratory analysis revealed that raw leafy vegetables contained 37 pesticide residues and metabolites with cyhalothrins (1.592, 2.930, and 4.069) mg/kg exceeding the MRLs of 0.7mg/kg. Whereas cooked samples contained only 19 pesticide residues and metabolites with chlorfenapyr (16.373, 4.566, 19.511, 2.228, 2.525, 2.596, 2.287, and 17.471) mg/kg exceeding the MRLs of 0.05 mg/kg. Fosetyl aluminum was within (MRLs) set by regulatory bodies in both cooked (0.043) mg/kg and raw samples (0.2, 0.1) mg/kg. Conclusion: The use of protective gear and proper vegetable covering are not consistently applied. Storage and handling conditions were suboptimal which may increasing the risk of microbial contamination. Also, pesticide residue was present in high concentration in the selected vegetable, which can cause health problems over time. This study highlights the urgent need for awareness of hygiene importance among vegetable handlers and stricter pesticide regulations in local markets.

Published in	American Journal of BioScience (Volume 14, Issue 2)
DOI	10.11648/j.ajbio.20261402.13
Page(s)	36-46
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Maximum Residue Limits, Food Safety, Pesticide Residue, Hygienic Practices

1. Introduction

Leafy vegetables are an important part of a healthy diet. They are a great source of fiber, antioxidants, iron, calcium, and other minerals in addition to vitamins A, C, and they’re low in calories

[14, 15]

. In Nigeria, leafy greens are a staple diet because they are high in nutrients and help provide food security. However, the cultivation, care and harvesting of these vegetables are very important and ensuring food safety across the supply chain is largely dependent on hygienic procedures. Farmers, transporters, and market vendors who handle vegetables come into direct touch with the crop, increasing the possibility of contamination if basic hygiene is not maintained. Poor hygiene procedures can lead to contaminants such as dirt, pesticide residues, and microbial infections, which can worsen the safety hazards related to these vegetables

[6]

Unsanitary practices, such as poor cleaning, exposure to environmental pollutants, improper storage, and handling of vegetables without protective measures, are common in many Nigerian marketplaces, including Bodija Market, a major market hub in Ibadan, where a variety of vegetables, including jute leaf, and different vegetables are sold. A substantial portion of the general population eats these vegetables because of their accessibility and health advantages. However, there are increasing doubts about these vegetables' safety, especially in regard to the possibility of pesticide residue contamination and improper handling procedures

[5]

. Also, large numbers of consumers purchase vegetables daily in this market, and understanding the hygienic conditions and pesticide residue levels in leafy vegetables is critical for public health interventions.

While pesticides aid in the management of pests and increase crop yields, if they are not applied correctly, vegetables may contain hazardous residues sometimes even surpassing the maximum residue limits (MRLs) set by international and national regulatory bodies by the time they are consumed

[7]

. According to the World Health Organization (WHO)

[18]

, approximately 3 million cases of pesticide poisoning occur each year, resulting in around 220,000 deaths, with a significant portion of these incidents linked to contaminated food and vegetables. Leafy vegetables are predicted to have significant residual pesticide levels due to their vast surface areas and the fact that pesticides are directly applied to their leaves

[10]

. Leafy vegetables such as jute leaf, Corchorus olitorius, are particularly vulnerable to pesticide contamination. While pesticides aid in the management of pests and increase crop yields, if they are not applied correctly, vegetables may contain hazardous residues sometimes even surpassing the maximum residue limits (MRLs) set by international and national regulatory bodies by the time they are consumed

[8]

. Environmental issues including poor sanitation, restricted access to clean water, and ignorance of food safety regulations can lead to the improper handling of vegetables in many developing nations, including Nigeria

[12]

. Also, Contamination of vegetables is sometimes caused by vegetable handlers using inadequate washing techniques, and a lack of protective gear

[4]

The elderly, children, and pregnant women are among the vulnerable groups that are most vulnerable because of their increased susceptibility to toxic exposures

[3]

. Pesticide residues in leafy vegetables can lead to both acute and chronic health problems. Acute exposure, often resulting from high levels of pesticide residues, can cause nausea, vomiting, dizziness, skin irritation, and neurological disorders. In extreme cases, poisoning may occur, leading to severe health complications or even death. Chronic exposure, on the other hand, has been linked to long-term health effects such as cancer, endocrine disruption, reproductive issues, and neurodevelopmental disorders

[10, 11]

Maximum Residue Limits (MRLs) for pesticide levels in food are set by regulatory bodies like Codex Alimentarius Commission and other international organizations, however, monitoring and enforcement in Nigeria, especially at the local market level, are still insufficient. Even though’ Bodija Market is one of the biggest vegetable markets in Ibadan, there is currently little information available about the amounts of pesticide residues in leafy vegetables sold there. Policymakers and health officials may find it difficult to adequately regulate and guarantee food safety due to the dearth of data

[8, 17]

. By providing evidence of pesticide residue levels in commonly consumed leafy vegetables, this study will fill a critical knowledge gap and guide policymakers in developing better regulations for the use of pesticides in vegetable production. Furthermore, it will help identify whether pesticide residue levels exceed the permissible limits, potentially prompting the need for stricter control measures and monitoring systems. In addition, little information is known about the levels of pesticide residues in vegetables sold at neighborhood markets and the hygienic conditions in which they are handled. It is uncertain how safe the vegetables that the population of Ibadan eat because of this lack of knowledge. Consumers may be unintentionally exposed to dangerous amounts of pesticide residues in the absence of proper assessment and monitoring,

[14, 16]

and there is a dearth of knowledge and instruction on safe food handling procedures in many developing nations, Nigeria inclusive. Therefore this study seeks to identify the hygienic practices among vegetable handlers and determines the presence of pesticide residues in a commonly consumed leafy vegetable sold in Ibadan major market.

2. Methods

2.1. Study Design

The descriptive cross-sectional study design and laboratory analysis was adopted. The study was conducted in two phases; use of a questionnaire to assess hygienic practices of vegetable handlers and laboratory analysis of vegetables to detect and quantify levels of pesticide residue using GC-MS.

2.2. Study Area

The study was carried out in bodija market in Ibadan North Local Government Area of Oyo State. Ibadan North (Figure 1) is located between latitude 7º 38'N to 7° 44´ N and longitude 3º 88' E and 3° 95´ E. Bodija Market (Figure 2) covers an area of approximately 7,207 m² (Oyo State of Nigeria 2009). The market is predominantly a food market. Goods sold in the market include vegetables, tubers, grains, cassava flakes, yam flour, frozen foods, electronics, shoes, bags, and plastics among others.

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Figure 1. Map of Ibadan North Local Government, Ibadan, Oyo State.

Download: Download full-size image

Figure 2. Map showing Bodija Market in Ibadan North Local Government.

2.3. Study Population

The target population in this study was consenting vegetable handlers at Bodija market that met the inclusion criteria. This population was chosen to ensure a wide range of perspectives on knowledge, attitude and practices regarding vegetable hygiene as vegetable handlers.

2.4. Sampling Techniques

A systematic sampling in which every n^th vegetable handler in the population were selected in bodija market. For pesticide residue testing, simple random sampling was used to select leafy vegetables from different sellers and points in the market in order to obtain representative samples.

2.5. Sample Size Determination

The sample size was determined using Fishers formula:

n = \frac{Z^{2} * p (1 - p)}{d^{2}}

(1)

Where:

n = the desired sample size when the population is greater than 10,000

Z = Z-score (e.g., 1.96 for 95% confidence)

P = expected proportion; 0.5 if unknown (Klunbut et al., 2017)

E = margin of error, normally set at 0.05

n = \frac{{1.96}^{2} * 0.5 (1 - 0.5)}{{0.05}^{2}}

n = 384.16 which is 384 respondents

Adjustment for a finite population

n = \frac{n_{0}}{\frac{1 + n_{0}}{N}}

(2)

Where:

n = Adjusted sample size for a finite population.

N = Total population size.

n = \frac{384}{\frac{1 + 384 - 1}{100}}

n= 79.5 which is approximately 80 respondents

2.6. Pesticide Residue Testing on Leafy Vegetables

The collection of the vegetable samples followed established guidelines set by the Codex Alimentarius. Samples were collected randomly from various locations to account for variability in pesticide application. After collection, samples were stored at low temperatures and transported in clean, sealed containers to the laboratory. The samples were washed to simulate consumer practices, then a portion of the leafy vegetable was boiled to represent cooked sample. Each samples were then homogenized to ensure uniformity. The AOAC 2007.01 method was adopted accommodating the use of QuEChERS procedure.

2.7. QuEChERS Procedure

Homogenized sample of the vegetable (10g) was weighed into a 50ml centrifuge tube, then 10ml of acetonitrile was added into the tube. The mixture was shaken in an orbital shaker for 5 minutes before buffer salt mix of 4g of magnesium sulfate anhydrous and 1g of sodium acetate was added into the tube to induce phase separation and isolate residues in the organic phase. The mixture was shaken again on the vortex mixer for 2 minutes. The sample was centrifuged for 15 minutes at 3000rpm to separate the solvent layer containing pesticides. Sample had intensively coloured extracts and was cleaned up using dispersive Solid-Phase Extraction (d-SPE) where alumina, graphitized carbon black and magnesium sulfate anhydrous were used to remove impurities such as pigments, fats, and plant debris, which may have interfered with analytical instruments. The centrifuge extract resulting from phase separation stage was used; 6ml of the supernatant was transferred into a 15ml clean up tube containing 900mg of magnesium sulfate, 45mg of graphitized carbon black (GCB) and 150mg of alumina. The mixture was shaken on the vortex mixer for 2 minutes then centrifuged for 10 minutes at 3000rpm. A 0.22 micrometre syringe was used to filter the supernatant into an autosampler vial.

The samples, including the quality control samples, were analysed by GC-MS. Quantification was based on two calibration curves (standards analysed before and after the samples). The curves were based on 3-5 matrix matched standard solutions, covering the relevant concentration range. Matrix-matched standards were prepared by adding a representative matrix gained by the same extraction method and cleanup procedure as for the sample.

2.8. MS Scanning in EI-mode from 50-400amu

The concentration of a pesticide in a sample was calculated on the basis of the standard calibration curve. The formula for the regression line is defined by y= αx+β, where α is the slope of the line and β is the intercept with the y-axis. The calibration curve was drawn up by the relative responses obtained when analysing the standards in relation to the internal standard (RP/RIP) as a function of the standard concentration. The content in the sample extract was calculated on the basis of the formula for the for the calibration curve.

For positive identification of a pesticide by GC-MS it was required that the retention time and mass spectrum for sample and standard coincide. For positive identification by GC-MS, it was required that the retention time of two ion transitions (quantifier and qualifier ions) coincide with that of the standard. The relative retention time of the analyte for GC corresponded to that of the calibration solution with a tolerance of ±0.5%. Results were expressed as pesticide concentrations (mg/kg) and compared against MRLs.

2.9. Data Analysis

All data were analysed using Microsoft Excel and Statistical Package for the Social Sciences (SPSS 21). The results were presented using simple percentage, mean, standard deviation of mean and ANOVA.

2.10. Ethical Considerations

Approval to conduct the research was obtained from the University of Ibadan/University College Hospital Ethics Review Committee with Institutional review board number 24/01010.

3. Results

3.1. Socio-Demographic Characteristics of Respondents

The age distribution shows that the majority (36.3%) of respondents were aged 36-45 years, while 20.0% were between 46-55 years. A smaller proportion (10.0%) fell within the 18-25 age group, indicating that the vegetable handling profession is dominated by older individuals. The distribution by gender shows that 86.3% of respondents were female, and only 13.8% were male reflecting a strong female involvement in the handling. The educational background of the respondents varied, with 31.3% having primary education, 25.0% having secondary education, and 11.3% attaining tertiary education. Notably, 22.5% of respondents had no formal education, which may have implications for their knowledge and adherence to hygiene practices. While, the market longevity data revealed that 43.0% of respondents had been selling vegetables for more than six years, demonstrating significant experience in the trade. Conversely, only 6.3% had been in the business for less than a year.

Table 1. Socio-demographic information of respondents.

Age Groups (n=80)	N	%
18-25	8	10.0
26-35	13	16.3
36-45	29	36.3
46-55	16	20.0
Above 55	14	17.5
Total	80	100.0
Gender (n=80)
Male	11	13.8
Female	69	86.3
Total	80	100.0
Level of Education (n=80)
No formal education	18	22.5
Primary education	25	31.3
Secondary education	20	25.0
Tertiary education	9	11.3
Vocational training	8	10.0
Total	80	100.0
Market Longevity (n=79)
6 months-1 year	5	6.3
1-3 years	20	25.3
4-6 years	20	25.3
More than 6 years	34	43.0
Total	79	100.0
Sales Demography (n=80)
Jute leaf (Ewedu)
Yes	56	70
No	24	30
Total	80	100

3.2. Knowledge of Hygiene and Food Safety Among Vegetable Handlers

The majority of respondents (82.5%) recognized dirty water as a major source of contamination. However, only 45.0% acknowledged handling with unclean hands as a risk factor, and 30.0% identified pesticides as potential contaminants. About 75.0% of respondents were aware of the importance of hygiene in vegetable handling, and 67.5% believed that proper hygiene reduces health risks. Furthermore, 65.0% agreed that poor hygiene negatively affects vegetable quality. Exactly 50.0% of respondents knew about protective clothing for vegetable handling, while the other half lacked this knowledge. Only 50.0% of respondents considered handwashing before handling vegetables necessary, and 40.0% emphasized the importance of keeping work areas clean. Surprisingly, 83.8% did not see the need to cover vegetables to prevent contamination. While 57.7% of respondents believed storage only increases shelf life, only 10.3% recognized its role in keeping vegetables clean and safe. Regarding storage practices, 93.75% of respondents do not use refrigeration, while 58.8% stored vegetables in a cool, dry place.

Table 2. Knowledge of hygiene practices among vegetable handlers.

Comon Sources of Contamination (n=80)	N	%
Dirty water
Yes	66	82.5
No	14	17.5
Total	80	100.0
Pesticides
Yes	24	30.0
No	56	70.0
Total	80	100.0
Handling by Unclean Hands
Yes	36	45.0
No	44	55.0
Total	80	100.0
Aware of Hygiene Importance (n=80)
Yes	60	75.0
No	20	25.0
Total	80	100.0
Believe Proper Hygiene Reduces health Risks (n=80)
Yes	54	67.5
No	26	32.5
Total	80	100.0
Believe unhygienic practices reduces vegetable quality (n=80)
Yes	52	65.0
No	28	35.0
Total	80	100.0
Knowledge of protective clothings for vegetable handlers (n=80)
Yes	40	50.0
No	40	50.0
Total	80	100.0

Do you believe are essential hygiene practices in vegetable handling? (n=80)
Washing hand before handling vegetable.
Yes	40	50.0
No	40	50.0
Total	80	100.0
Keeping work areas clean
Yes	32	40.0
No	48	60.0
Total	80	100.0
Covering vegetables to prevent contamination
Yes	13	16.3
No	67	83.8
Total	80	100.0
Using clean water to wash vegetable
Yes	64	80.0
No	16	20.0
Total	80	100.0
What is the role of storage in vegetable hygiene?(n=78)
To keep vegetables clean and safe	8	10.3
To increase shelf life only	45	57.7
It has no role	22	28.2
I don’t know	3	3.8
Total	78	100.0
Storage of Unsold vegetables (n=80)
Refrigeration
Yes	5	6.25
No	75	93.75
Total	80	100
Kept in a cool, dry place
Yes	47	58.8
No	33	41.3
Total	80	100.0
Left out in the open
Yes	28	35
No	52	65
Total	80	100

Hygiene Practices of Vegetable Handlers

Hygiene practices were evaluated based on a four-point Likert scale, with responses categorized as "Always," "Sometimes," "Rarely," or "Never." The results are summarized in Table 3.

Handwashing

The mean score for washing hands before handling vegetables was 2.75, indicating that respondents were "likely" to engage in this practice. However, the use of soap or sanitizer was lower (M=1.75), meaning it was "unlikely."

Cleaning of Work Areas

The highest adherence was observed in work area cleaning, with a mean score of 3.81, showing that most respondents cleaned their workspaces "very likely."

Washing Vegetables before Selling

The mean score of 3.05 suggests that respondents were "likely" to wash vegetables before sale.

Use of Protective Gear

The mean score of 1.63 indicated that wearing protective gear was "very unlikely" among respondents.

Covering Vegetables

With a mean score of 2.09, covering vegetables was rated as "unlikely."

Separation of Damaged Vegetables

The mean score of 3.30 suggests that respondents were "very likely" to separate damaged or contaminated vegetables from fresh ones.

Table 3. Hygiene practices carried out on vegetables.

Statement	N	Minimum	Maximum	Mean	Std. Deviation
Do you wash your hands before handling vegetables	80	1	4	2.75	.834
Do you use soap and sanitizer to clean your hand before handling vegetables	80	1	4	1.75	.935
Do you clean your working area (tables, baskets) everyday	80	1	4	3.81	.553
Do you wash the vegetables before selling them?	79	1	4	3.05	.830
Do you wear any protective gear while handling vegetables (e.g., gloves, apron)	80	1	4	1.63	.862
Do you cover your vegetables to protect them from dust and flies	80	1	4	2.09	.903
Do you separate damaged or contaminated vegetables from fresh ones?	80	1	4	3.30	.701

Comparison between the Isolated Pesticide Residues and Metabolites of Raw and Cooked Vegetables

The raw leafy vegetables has 37 isolated pesticides and metabolites compared to 19 of the cooked leafy vegetables showing a significantly lower amount of pesticide residues.

Table 4. Comparison between the Isolated Pesticide Residues and Metabolites of Raw and Cooked Vegetables.

S/N	Pesticide Identified
	Raw Leafy Vegetables		Cooked Leafy Vegetables
1	Cyclobutanecarbonitrile	1	Chlorfenapyr
2	Cyclononasiloxane, octadecameth	2	alpha-Methylstyrene
3	Cyclopentene, 3-undecyl-	3	Ethanol, pentamethyl-
4	1-Nonen-3-ol	4	Terbutaline, N-trifluoroacetyl-
5	Dichloromethyldimethylsilyloxyb	5	Cyclononasiloxane, octadecameth
6	Allyl fluoride	6	Hexadecenoic acid, Z-11-
7	17-Octadecynoic acid	7	3, 7, 11, 15-Tetramethyl-2-hexadec
8	Octanoic Acid	8	3-Eicosyne
9	Phosphonic acid, (p-hydroxyphen	9	3, 7, 11, 15-Tetramethyl-2-hexadec
10	Cyclopentadecanol	10	n-Hexadecanoic acid
11	Nonanoic acid	11	Triacontyl trifluoroacetate
12	Pentadecanoic acid, 14-methyl-,	12	Heptadecanoic acid
13	trans-13-Octadecenoic acid	13	Squalene
14	9, 12-Octadecadienoic acid (Z, Z)	14	Octadecanoic acid
15	n-Decanoic acid	15	Phthalic acid, 6-ethyloct-3-yl
16	Oleic Acid	16	Triacontyl trifluoroacetate
17	Dodecanoic acid	17	9, 10-Anthracenedione, 2-methyl-
18	Phytol	18	Triacontyl trifluoroacetate
19	Phenanthrene	19	beta-Sitosterol acetate
20	1, 2-Benzenedicarboxylic acid
21	Tetradecanoic acid
22	Pentadecanoic acid
23	Oleic Acid
24	Pentadecanoic acid
25	2 (3H)-Furanone, 5-dodecyldihydr
26	Tetratriacontyl heptafluorobuty
27	Butyl 9-hexadecenoate
28	n-Hexadecanoic acid
29	n-Propyl 9-hexadecenoate
30	Eicosanoic acid
31	6-Octadecenoic acid
32	1, 6, 10, 14, 18, 22-Tetracosahexaen
33	Octadecanoic acid
34	6-Octadecenoic acid
35	Phthalic acid, 6-ethyloct-3-yl
36	Hexadecanamide
37	Tetratriacontyl pentafluoroprop

Comparison of pesticide residue and metabolite detected in raw leafy vegetable with Codex Alimentarius Commission (2019).

Table 5. Comparison of pesticide residue and metabolite detected in raw leafy vegetable with Codex Alimentarius Commission.

S/N	Pesticide residue and metabolite	Detected concentration (mg\kg)	MRL set by Codex Alimentarius Commission (mg\kg)	Status
1	Cyhalothrins	1.592, 0.440, 2.930, 4.069, 0.149 and 0.007	0.7	Exceed
2	Fosetyl aluminium	0.2, 0.1	20	Within

Comparison of pesticide residue and metabolite detected in cooked leafy vegetable with Codex Alimentarius Commission (2019).

Table 6. Comparison of pesticide residue and metabolite detected in cooked leafy vegetable with Codex Alimentarius Commission (2019).

S/N	Pesticide residue and metabolite	Detected concentration (mg\kg)	MRL set by Codex Alimentarius Commission (mg\kg)	Status
1	Chlorfenapyr	16.373, 4.566, 19.511, 2.228, 2.525, 2.596, 2.287, 17.471, 0.069, 0.086	0.05	Exceeds
2	Fosetyl aluminium	0.043	20	Within

3.3. Comparison Between the Isolated Pesticide Residues and Metabolites of Raw and Cooked Vegetables

The laboratory analysis revealed that raw leafy vegetables contained 37 pesticide residues and metabolites, whereas cooked samples contained only 19. This significant reduction suggests the efficacy of cooking in degrading many pesticide compounds. However, it is noteworthy that at least one compound in both raw and cooked samples exceeded the Maximum Residue Limits (MRLs) set by Codex Alimentarius Commission (2019). Fosetyl aluminium was within Maximum Residue Limits (MRLs) in both cooked and raw samples. It however underwent a 78.5% reduction from 0.2mg/kg to 0.043mg/kg after 15 minutes cooking time with a degradation rate of 10.25% per minute. The results underscore the importance of both pre-harvest pesticide management and post-harvest handling practices to safeguard public health.

4. Discussion

This study provides important insights into the dual burden of poor hygienic practices and pesticide contamination in leafy vegetables sold in Bodija Market, Ibadan. The findings highlight significant public health concerns, particularly in relation to food safety, exposure to pesticide residues, and the behavioral practices of vegetable handlers.

The socio-demographic profile revealed that vegetable handling is predominantly carried out by middle-aged women with relatively low levels of formal education. This aligns with findings from studies in Ghana and Ethiopia, where informal food handling sectors are largely dominated by women with limited formal education, which often influences adherence to food safety practices. For instance, it was reported that lower educational attainment among food handlers was significantly associated with poor hygiene knowledge and practices

[7, 13]

. The implication is that educational status may play a critical role in shaping awareness and compliance with recommended hygiene standards.

Although a high proportion of respondents demonstrated awareness of the importance of hygiene, this did not consistently translate into practice. Only few practiced handwashing before handling vegetables, and an even smaller proportion used soap or sanitizer. This gap between knowledge and practice is consistent with previous studies

[2, 6]

, which emphasized that awareness alone does not guarantee behavioral change in food safety practices. Similarly, the low usage of protective gear and poor practice in covering vegetables indicate significant lapses in basic food safety measures. Comparable findings were reported by Alemu et al. (2018), who observed widespread unhygienic handling of vegetables in local markets, contributing to contamination risks.

The laboratory analysis revealed the presence of multiple pesticide residues in both raw and cooked samples of Corchorus olitorius. The detection of 37 residues in raw samples compared to 19 in cooked samples demonstrates that cooking significantly reduces pesticide load. This finding is consistent with previous studies

[13]

, which reported that thermal processing can degrade certain pesticide compounds. However, despite this reduction, some residues—particularly cyhalothrins in raw samples and chlorfenapyr in cooked samples exceeded the Maximum Residue Limits (MRLs) established by Codex Alimentarius Commission. The presence of cyhalothrins above MRLs in raw vegetables corroborates previous findings

[8]

, who also reported elevated pesticide residues in vegetables sold in Ibadan markets. Similarly, studies in India

[9]

and Pakistan

[1]

have documented pesticide levels in vegetables exceeding safety thresholds, indicating a widespread issue in developing countries. The persistence of chlorfenapyr at concentrations far above permissible limits even after cooking is particularly alarming, suggesting that some pesticides are resistant to thermal degradation and may pose long-term health risks.

Fosetyl aluminium, however, remained within acceptable limits in both raw and cooked samples, which is consistent with its relatively lower toxicity and higher degradation rate reported in previous studies

[12, 17]

. The observed reduction after cooking further supports the role of food processing in mitigating pesticide exposure, although it does not completely eliminate risk. The findings of this study reinforce concerns raised by the World Health Organization

[18]

regarding the global burden of pesticide exposure, especially in low- and middle-income countries where regulatory enforcement is weak. The combination of poor hygiene practices and high pesticide residues creates a compounded risk for consumers, potentially leading to both acute and chronic health effects, including foodborne illnesses, endocrine disruption, and carcinogenic outcomes.

Overall, this study is consistent with existing literature in demonstrating that food safety challenges in developing countries are multifactorial, involving behavioral, environmental, and regulatory dimensions. However, it also contributes uniquely by combining both behavioral assessment and laboratory analysis, thereby providing a more comprehensive understanding of the risks associated with leafy vegetable consumption in local markets.

5. Conclusion

The findings indicates that vegetable handlers play an essential role in the food supply chain, however, there is a gap in their knowledge and practice of proper hygiene and food safety measures. The socio-demographic profile of vegetable handlers shows that the trade is predominantly carried out by experienced, middle-aged women, with many having limited formal education. The study also concluded that essential practices such as thorough hand washing with soap, use of protective gear, and proper vegetable covering are not consistently applied. Moreover, storage practices are suboptimal, as the majority of vendors do not use refrigeration and instead rely on open or inadequately protected storage methods. The study identified significant contamination risks from poor hygiene practices which can lead to foodborne illnesses. Furthermore, the laboratory analysis of Corchorus olithorus confirmed the presence of pesticide residues, some of which exceeded the Maximum Residue Limits (MRLs). The study also concluded that cooking substantially reduces pesticide residue levels through thermal degradation and leaching. Pesticides such as cyhalothrins and chlorfenapyr were detected at unsafe levels, raising concerns about potential health risks. Despite evidence that washing and cooking can reduce pesticide residues. It is therefore recommended that there is need for urgent policy interventions, improved regulation, and enhanced education among vegetable handlers and consumers. Addressing these issues will require a multi-faceted approach involving government agencies, regulatory bodies, market authorities, farmers, and consumers to ensure food safety and public health protection.

6. Recommendations

Based on the findings of this study, there is a need for continuous education and capacity-building programs for vegetable handlers on proper hygiene practices, including hand washing with soap, use of protective gear, and safe storage methods. Training should be tailored to accommodate low literacy levels. Also, government agencies such as NAFDAC and other food safety authorities should intensify monitoring and enforcement of pesticide use regulations. Regular inspection of farms and markets should be conducted to ensure compliance with established MRLs. In addition, farmers should be educated on the proper application of pesticides, including adherence to recommended dosages and observance of pre-harvest intervals (withholding periods). Integrated Pest Management (IPM) strategies should be encouraged to reduce reliance on chemical pesticides. Periodic testing of vegetables for pesticide residues should be institutionalized, particularly in major markets. This will help detect contamination early and protect public health. Furthermore, policymakers should develop and implement comprehensive food safety policies that address both pre-harvest and post-harvest practices. Collaboration between agricultural, health, and environmental sectors is essentials and future studies should explore long-term health outcomes associated with dietary exposure to pesticide residues and assess the effectiveness of intervention strategies.

Abbreviations

MRLs	Maximum Residue Limits
WHO	World Health Organization
GC-MS	Gas Chromatography Mass Spectrometry
AOAC	Association of Official Analytical Chemist
QuEChERS	Quick, Easy, Cheap, Effective, Rugged and Safe
d-SPE	Dispersive Solid-Phase Extraction
GCB	Graphitized Carbon Black
RP	Relative Peak
RIP	Relative Ion Pair
EI	Electron Ionization
ANOVA	Analysis of Variance
SPSS 21	Statistical Package for Social Sciences (Version 21)
M	Mean Score
IPM	Integrated Pest Management
NAFDAC	National Agency for Food and Drug Administration and Control

Author Contributions

Dada Abiodun: Methodology, Supervision, Writing – review & editing

Okareh Oladapo: Conceptualization, Supervision

Opawade Dolapo: Investigation, Project Administration, Writing – original draft

Awopetu Niyi: Data analysis, Fund acquisition

Funding

The authors received no fund from any sources as such, the research work was self-funded.

Conflicts of Interest

The authors declare no conflict of interest

References

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[2]	Adegbola, J. A., Anugwon, H. D., Awagu, F., & Audu, E. A. (2012). The concept of withholding period and pesticide residues in grain storage. Asian Journal of Agriculture and Rural Development. 2(4), 598-603.
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[6]	Augustin, J. C., Kooh, P., Bayeux, T., Guillier, L., Meyer, T., Jourdan-Da Silva, N., Villena, I., Sanaa, M., & Cerf, O. (2020). Contribution of Foods and Poor Food-Handling Practices to the Burden of Foodborne Infectious Diseases in France. Foods, 9(11), 1644. https://doi.org/10.3390/foods9111644
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[12]	Kim, S.-K., Oh, H.-J., Oh, S.-S., & Koh, S.-B. (2022). Pesticide Exposure in Relation to the Incidence of Abnormal Glucose Regulation: A Retrospective Cohort Study. International Journal of Environmental Research and Public Health, 19(12), 7550. https://doi.org/10.3390/ijerph19127550
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[14]	Machado‐Moreira, B., Richards, K., Brennan, F., Abram, F., & Burgess, C. M. (2019b). Microbial Contamination of Fresh Produce: What, Where, and How? Comprehensive Reviews in Food Science and Food Safety, 18(6), 1727-1750. https://doi.org/10.1111/1541-4337.12487
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Abiodun, D., Oladapo, O., Dolapo, O., Niyi, A. (2026). Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria. American Journal of BioScience, 14(2), 36-46. https://doi.org/10.11648/j.ajbio.20261402.13

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ACS Style

Abiodun, D.; Oladapo, O.; Dolapo, O.; Niyi, A. Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria. Am. J. BioScience 2026, 14(2), 36-46. doi: 10.11648/j.ajbio.20261402.13

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AMA Style

Abiodun D, Oladapo O, Dolapo O, Niyi A. Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria. Am J BioScience. 2026;14(2):36-46. doi: 10.11648/j.ajbio.20261402.13

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@article{10.11648/j.ajbio.20261402.13,
  author = {Dada Abiodun and Okareh Oladapo and Opawade Dolapo and Awopetu Niyi},
  title = {Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria},
  journal = {American Journal of BioScience},
  volume = {14},
  number = {2},
  pages = {36-46},
  doi = {10.11648/j.ajbio.20261402.13},
  url = {https://doi.org/10.11648/j.ajbio.20261402.13},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajbio.20261402.13},
  abstract = {Introduction: Leafy vegetables are a vital part of a balanced diet due to their high nutritional content, including fibre, vitamins, and minerals. However, there are concerns about the safety of the vegetables due to contamination from poor hygienic handling and pesticide residues. Major health problems associated with vegetables that contains pesticides residues are immunological suppression, hormonal changes and occurrence of different cancers. There are limited studies on the safety practices of vegetable handlers and isolated pesticides of raw and cooked vegetables. Hence, this study investigates the hygienic practices among vegetable handlers and levels of pesticide residues in a commonly consumed leafy vegetable. Methods: A descriptive cross-sectional study design and laboratory analysis was used. Through random sampling, 80 vegetable handlers in Bodija market were selected. Data on hygiene knowledge, attitudes and practices were obtained using structured questionnaires. Pesticide residues in Corchorus olitorius vegetable was analyzed using QuEChErs and Gas chromatography-Mass Spectrometry (GC-MS). The data was presented in mean, standard deviation, simple percentage and charts. The result was compared to the Maximum Residue Limits (MRLs) set by Codex Alimentarius Commission. Results: The study shows that 86.3% of respondents were female, and 13.8% were male. Majority of the respondents (82.5%) recognized dirty water used for washing the vegetables as a major source of contamination while 45.0% acknowledged handling with unclean hands as a risk factor, and 30.0% identified pesticides as potential contaminants. Only 65.0% noted poor hygiene could affects quality of vegetable. However, 50.0% practiced hand washing, and 83.8% saw no need to cover their vegetables. The laboratory analysis revealed that raw leafy vegetables contained 37 pesticide residues and metabolites with cyhalothrins (1.592, 2.930, and 4.069) mg/kg exceeding the MRLs of 0.7mg/kg. Whereas cooked samples contained only 19 pesticide residues and metabolites with chlorfenapyr (16.373, 4.566, 19.511, 2.228, 2.525, 2.596, 2.287, and 17.471) mg/kg exceeding the MRLs of 0.05 mg/kg. Fosetyl aluminum was within (MRLs) set by regulatory bodies in both cooked (0.043) mg/kg and raw samples (0.2, 0.1) mg/kg. Conclusion: The use of protective gear and proper vegetable covering are not consistently applied. Storage and handling conditions were suboptimal which may increasing the risk of microbial contamination. Also, pesticide residue was present in high concentration in the selected vegetable, which can cause health problems over time. This study highlights the urgent need for awareness of hygiene importance among vegetable handlers and stricter pesticide regulations in local markets.},
 year = {2026}
}

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TY - JOUR
T1 - Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria
AU - Dada Abiodun
AU - Okareh Oladapo
AU - Opawade Dolapo
AU - Awopetu Niyi
Y1 - 2026/04/15
PY - 2026
N1 - https://doi.org/10.11648/j.ajbio.20261402.13
DO - 10.11648/j.ajbio.20261402.13
T2 - American Journal of BioScience
JF - American Journal of BioScience
JO - American Journal of BioScience
SP - 36
EP - 46
PB - Science Publishing Group
SN - 2330-0167
UR - https://doi.org/10.11648/j.ajbio.20261402.13
AB - Introduction: Leafy vegetables are a vital part of a balanced diet due to their high nutritional content, including fibre, vitamins, and minerals. However, there are concerns about the safety of the vegetables due to contamination from poor hygienic handling and pesticide residues. Major health problems associated with vegetables that contains pesticides residues are immunological suppression, hormonal changes and occurrence of different cancers. There are limited studies on the safety practices of vegetable handlers and isolated pesticides of raw and cooked vegetables. Hence, this study investigates the hygienic practices among vegetable handlers and levels of pesticide residues in a commonly consumed leafy vegetable. Methods: A descriptive cross-sectional study design and laboratory analysis was used. Through random sampling, 80 vegetable handlers in Bodija market were selected. Data on hygiene knowledge, attitudes and practices were obtained using structured questionnaires. Pesticide residues in Corchorus olitorius vegetable was analyzed using QuEChErs and Gas chromatography-Mass Spectrometry (GC-MS). The data was presented in mean, standard deviation, simple percentage and charts. The result was compared to the Maximum Residue Limits (MRLs) set by Codex Alimentarius Commission. Results: The study shows that 86.3% of respondents were female, and 13.8% were male. Majority of the respondents (82.5%) recognized dirty water used for washing the vegetables as a major source of contamination while 45.0% acknowledged handling with unclean hands as a risk factor, and 30.0% identified pesticides as potential contaminants. Only 65.0% noted poor hygiene could affects quality of vegetable. However, 50.0% practiced hand washing, and 83.8% saw no need to cover their vegetables. The laboratory analysis revealed that raw leafy vegetables contained 37 pesticide residues and metabolites with cyhalothrins (1.592, 2.930, and 4.069) mg/kg exceeding the MRLs of 0.7mg/kg. Whereas cooked samples contained only 19 pesticide residues and metabolites with chlorfenapyr (16.373, 4.566, 19.511, 2.228, 2.525, 2.596, 2.287, and 17.471) mg/kg exceeding the MRLs of 0.05 mg/kg. Fosetyl aluminum was within (MRLs) set by regulatory bodies in both cooked (0.043) mg/kg and raw samples (0.2, 0.1) mg/kg. Conclusion: The use of protective gear and proper vegetable covering are not consistently applied. Storage and handling conditions were suboptimal which may increasing the risk of microbial contamination. Also, pesticide residue was present in high concentration in the selected vegetable, which can cause health problems over time. This study highlights the urgent need for awareness of hygiene importance among vegetable handlers and stricter pesticide regulations in local markets.
VL - 14
IS - 2
ER -

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Author Information

Dada Abiodun

Department of Environmental Health Technology, Ekiti State College of Technology, Ijero Ekiti, Nigeria

Contact Email

http://orcid.org/0000-0003-1912-5578
Okareh Oladapo

Department of Environmental Health Sciences, University of Ibadan, Ibadan, Nigeria

http://orcid.org/0000-0003-4988-6749
Opawade Dolapo

Department of Environmental Health Sciences, University of Ibadan, Ibadan, Nigeria
Awopetu Niyi

Department of Computer Studies, Ekiti State College of Technology, Ijero Ekiti, Nigeria

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Abiodun, D., Oladapo, O., Dolapo, O., Niyi, A. (2026). Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria. American Journal of BioScience, 14(2), 36-46. https://doi.org/10.11648/j.ajbio.20261402.13

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ACS Style

Abiodun, D.; Oladapo, O.; Dolapo, O.; Niyi, A. Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria. Am. J. BioScience 2026, 14(2), 36-46. doi: 10.11648/j.ajbio.20261402.13

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AMA Style

Abiodun D, Oladapo O, Dolapo O, Niyi A. Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria. Am J BioScience. 2026;14(2):36-46. doi: 10.11648/j.ajbio.20261402.13

Copy | Download

@article{10.11648/j.ajbio.20261402.13,
  author = {Dada Abiodun and Okareh Oladapo and Opawade Dolapo and Awopetu Niyi},
  title = {Pesticide Residue in Leafy Vegetables and Hygienic Practices of Handlers in a Major Market in Ibadan, Nigeria},
  journal = {American Journal of BioScience},
  volume = {14},
  number = {2},
  pages = {36-46},
  doi = {10.11648/j.ajbio.20261402.13},
  url = {https://doi.org/10.11648/j.ajbio.20261402.13},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajbio.20261402.13},
  abstract = {Introduction: Leafy vegetables are a vital part of a balanced diet due to their high nutritional content, including fibre, vitamins, and minerals. However, there are concerns about the safety of the vegetables due to contamination from poor hygienic handling and pesticide residues. Major health problems associated with vegetables that contains pesticides residues are immunological suppression, hormonal changes and occurrence of different cancers. There are limited studies on the safety practices of vegetable handlers and isolated pesticides of raw and cooked vegetables. Hence, this study investigates the hygienic practices among vegetable handlers and levels of pesticide residues in a commonly consumed leafy vegetable. Methods: A descriptive cross-sectional study design and laboratory analysis was used. Through random sampling, 80 vegetable handlers in Bodija market were selected. Data on hygiene knowledge, attitudes and practices were obtained using structured questionnaires. Pesticide residues in Corchorus olitorius vegetable was analyzed using QuEChErs and Gas chromatography-Mass Spectrometry (GC-MS). The data was presented in mean, standard deviation, simple percentage and charts. The result was compared to the Maximum Residue Limits (MRLs) set by Codex Alimentarius Commission. Results: The study shows that 86.3% of respondents were female, and 13.8% were male. Majority of the respondents (82.5%) recognized dirty water used for washing the vegetables as a major source of contamination while 45.0% acknowledged handling with unclean hands as a risk factor, and 30.0% identified pesticides as potential contaminants. Only 65.0% noted poor hygiene could affects quality of vegetable. However, 50.0% practiced hand washing, and 83.8% saw no need to cover their vegetables. The laboratory analysis revealed that raw leafy vegetables contained 37 pesticide residues and metabolites with cyhalothrins (1.592, 2.930, and 4.069) mg/kg exceeding the MRLs of 0.7mg/kg. Whereas cooked samples contained only 19 pesticide residues and metabolites with chlorfenapyr (16.373, 4.566, 19.511, 2.228, 2.525, 2.596, 2.287, and 17.471) mg/kg exceeding the MRLs of 0.05 mg/kg. Fosetyl aluminum was within (MRLs) set by regulatory bodies in both cooked (0.043) mg/kg and raw samples (0.2, 0.1) mg/kg. Conclusion: The use of protective gear and proper vegetable covering are not consistently applied. Storage and handling conditions were suboptimal which may increasing the risk of microbial contamination. Also, pesticide residue was present in high concentration in the selected vegetable, which can cause health problems over time. This study highlights the urgent need for awareness of hygiene importance among vegetable handlers and stricter pesticide regulations in local markets.},
 year = {2026}
}

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